1. Field of the Invention
This invention pertains generally to a device for stopping a load in a vertical shaft and more particularly to a gravity brake that stops a load being lowered or raised in a vertical shaft after failure of a suspending member.
2. Description of the Background Art
When loads are hoisted within a vertical shaft, the load is suspended from a support member, such as a cable, and moved in a slow ascent or descent within the shaft to a desired position by means of a manual or motor-driven hoist system. Certain catastrophic failures of the supporting members or hoist system can allow the load to free fall down the shaft. Obviously such a situation can be destructive for both the load and the shaft. Furthermore, under certain conditions the free falling load poses a danger to personnel.
Therefore a need exists for a device that can stop a load from rapidly descending down a shaft should the hoisting mechanism fail. The gravity brake in accordance with the present invention satisfies that need, as well as others, and overcomes deficiencies in previously known techniques.